import {cmp, copyPos, equalCursorPos, maxPos, minPos} from "../line/pos.js"
import {indexOf} from "../util/misc.js"

// Selection objects are immutable. A new one is created every time
// the selection changes. A selection is one or more non-overlapping
// (and non-touching) ranges, sorted, and an integer that indicates
// which one is the primary selection (the one that's scrolled into
// view, that getCursor returns, etc).
export class Selection {
    constructor(ranges, primIndex) {
        this.ranges = ranges
        this.primIndex = primIndex
    }

    primary() {
        return this.ranges[this.primIndex]
    }

    equals(other) {
        if (other == this) return true
        if (other.primIndex != this.primIndex || other.ranges.length != this.ranges.length) return false
        for (let i = 0; i < this.ranges.length; i++) {
            let here = this.ranges[i], there = other.ranges[i]
            if (!equalCursorPos(here.anchor, there.anchor) || !equalCursorPos(here.head, there.head)) return false
        }
        return true
    }

    deepCopy() {
        let out = []
        for (let i = 0; i < this.ranges.length; i++)
            out[i] = new Range(copyPos(this.ranges[i].anchor), copyPos(this.ranges[i].head))
        return new Selection(out, this.primIndex)
    }

    somethingSelected() {
        for (let i = 0; i < this.ranges.length; i++)
            if (!this.ranges[i].empty()) return true
        return false
    }

    contains(pos, end) {
        if (!end) end = pos
        for (let i = 0; i < this.ranges.length; i++) {
            let range = this.ranges[i]
            if (cmp(end, range.from()) >= 0 && cmp(pos, range.to()) <= 0)
                return i
        }
        return -1
    }
}

export class Range {
    constructor(anchor, head) {
        this.anchor = anchor;
        this.head = head
    }

    from() {
        return minPos(this.anchor, this.head)
    }

    to() {
        return maxPos(this.anchor, this.head)
    }

    empty() {
        return this.head.line == this.anchor.line && this.head.ch == this.anchor.ch
    }
}

// Take an unsorted, potentially overlapping set of ranges, and
// build a selection out of it. 'Consumes' ranges array (modifying
// it).
export function normalizeSelection(cm, ranges, primIndex) {
    let mayTouch = cm && cm.options.selectionsMayTouch
    let prim = ranges[primIndex]
    ranges.sort((a, b) => cmp(a.from(), b.from()))
    primIndex = indexOf(ranges, prim)
    for (let i = 1; i < ranges.length; i++) {
        let cur = ranges[i], prev = ranges[i - 1]
        let diff = cmp(prev.to(), cur.from())
        if (mayTouch && !cur.empty() ? diff > 0 : diff >= 0) {
            let from = minPos(prev.from(), cur.from()), to = maxPos(prev.to(), cur.to())
            let inv = prev.empty() ? cur.from() == cur.head : prev.from() == prev.head
            if (i <= primIndex) --primIndex
            ranges.splice(--i, 2, new Range(inv ? to : from, inv ? from : to))
        }
    }
    return new Selection(ranges, primIndex)
}

export function simpleSelection(anchor, head) {
    return new Selection([new Range(anchor, head || anchor)], 0)
}
